Kwok Chi Hang. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references. / Abstracts in English and Chinese. / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- All-Optical Signal Processing in Optical Communications --- p.2 / Chapter 1.2 --- Fiber-Based Optical Kerr Nonlinear Switches --- p.5 / Chapter 1.3 --- Highly Nonlinear Fibers --- p.6 / Chapter 1.4 --- Objectives and Scope of Study --- p.8 / Chapter 1.5 --- Summary --- p.9 / Chapter Chapter 2 --- Optical Nonlinearity --- p.14 / Chapter 2.1 --- Fiber Nonlinearity --- p.15 / Chapter 2.2 --- Dispersion --- p.21 / Chapter 2.3 --- Cross-Phase Modulation --- p.26 / Chapter 2.4 --- Cross-Polarization Modulation --- p.29 / Chapter Chapter 3 --- Fibers: The Nonlinear Media --- p.47 / Chapter 3.1 --- Average Dispersion --- p.48 / Chapter 3.2 --- Longitudinal Dispersion Map --- p.53 / Chapter 3.3 --- Nonlinear Refractive Index and Nonlinear Coefficient --- p.57 / Chapter 3.4 --- Electrostrictive Contribution --- p.62 / Chapter 3.5 --- List of the Fiber Properties --- p.66 / Chapter Chapter 4 --- Multi-Wavelength Nonlinear Signal Processing --- p.69 / Chapter 4.1 --- Challenge --- p.70 / Chapter 4.2 --- Applications --- p.72 / Chapter 4.3 --- Proposed System Application --- p.110 / Chapter Chapter 5 --- Conclusion and Future Work --- p.114 / Chapter 5.1 --- Comparisons between Proposed and Existing Approaches --- p.114 / Chapter 5.2 --- Conclusion of the Dissertation --- p.115 / Chapter 5.3 --- Prospects and Directions of Future Work --- p.117 / Appdenix A Numerical Model for Dispersion Calculation --- p.I / Appdenix B Simulation Model of Wide Band Cross-Polarization Switch --- p.III / Appdenix C Simulation Model of Spectral Filtering under XPM --- p.VI / List of Publications --- p.IX

by Chun-kit Chan. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references (p. 143-158). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web.

Les composés multimatériaux à base de verre connaissent aujourd’hui un intérêt croissant, en particulier sous la forme de fibres optique pour des applications dans l’infrarouge. Parmi les matériaux vitreux qui existent, les verres chalcogénures présentent de nombreux avantages, tel qu’un large domaine de transparence allant du visible à l’infrarougeou encore de bonne aptitude à pouvoir être étirer. Pour réaliser de nouvelles fibres multimatériaux, il est important d’avoir accès à un choix étendu de compositions vitreuses étirables pouvant servir de matrice hôte. Il peut être montré que les verres actuellement utilisés pour la réalisation de fibres multimatériaux couvrent deux plages de température de transition vitreuse différentes ; soit à basse température (100-250 °C), ou à haute température (1000 °C et plus). Le manque d’information sur des verres étirables couvrant un domaine intermédiaire de température entre 250 et 1000 °C, nous ont conduit à explorer les propriétés et les capacités d’étirement des verres des deux systèmes ternaires Ge-S-I et Ga-As-S. Il sera montré que ces systèmes vitreux ont en effet des Tg permettant de couvrir cette gamme intermédiaire de température et ont de larges domaines de formation vitreux. Un ensemble de caractérisations physiques et thermiques sur les verres au sein des systèmes ternaires Ge-S-I et Ge-As-S seront présentés et analysés. Il sera possible d’observer, comment notamment les résultats des mesures thermomécaniques et de viscosité des échantillons synthétisés ont permis d’aborder dans les meilleures conditions les tests d’étirement des verres. Ou encore comment l’analyse minutieuse des propriétés a pu permettre de définir un domaine de composition combinant à la fois des propriétés optimales en termes de Tg et de transparence dans le visible, avec une bonne capacité à pouvoir être étirées sous forme de fibres optiques. Pour la première fois les domaines de fibrage des deux ternaires à partir de l’étirement d’une préforme seront présentés dans ce manuscrit. Ce travail présente également une caractérisation structurale des verres Ge-S-I. Cette étude a été réalisé en combinant la spectroscopie Raman, la spectroscopie IR et des calculs de chimie théorique afin de proposer un nouveau modèle structural basé sur les avancés les plus récentes d'une part sur la structure du système binaire Ge-S, puis ternaire Ge-S-I.Enfin, les résultats préliminaires sur la réalisation de fibres multimatériaux à partir de verres Ge-S-I et Ge-As-S pour la réalisation de sources laser entre 3 et 5 µm, seront présentés. Le projet, la méthodologie et les résultats quant à la réalisation d’une fibre multimatériaux à base de verre chalcogénure avec un cœur cristallisé de ZnS à partir de deux techniques innovantes différentes, seront présentés. / Nowadays, the interest on multimaterials based on glass matrix growth constantly, in particular in the field of multimaterial optical fibers for IR applications. Among the glass materials that exist, chalcogenide glasses presents a lot of advantages as for instance large transparency windows, spanning from the visible to the infrared or also good capability to be drawn. In the aim to realize new multimaterials fibers, it is important to get a large choice of draw able glass compositions that can be used as host matrix. It can be shown that the glass used currently to make multimaterial fibers covers two glass transition temperature range ; low temperature (100-250 °C) and high temperature (1000 °C and more). The lack of information regarding the existence of glass compositions that can be drawn into fibers at intermediate temperature (between 250 and 1000 °C), has lead us to explore the properties and the draw ability of glasses into two ternary systems: Ge-As-S and Ge-S-I. It will be presented that these glass systems possess Tg that covers this intermediate range of temperature and have large glass forming regions. Some physical and thermal characterizations of Ge-As-S and Ge-S-I glasses will be presented and analyzed. It will be possible to observe how the thermomechanical and viscosity measurements made on the different samples enabled us to perform the drawing tests in the best conditions. It will be also possible to see how a careful analysis of the Ge-S-I glass properties gave us the possibility to define a glass region combining optimal properties as Tg and transparency in the visible, and good capability to be drawn. For the first time, the fiber drawing region of both systems will be presented in this thesis. This work present also a structural characterization of Ge-S-I glasses using IR and Raman spectroscopy as well as DFT calculations, in the aim to propose a new structural model based on recent development in the Ge-S network structure. Finally, preliminary results on the realization of Ge-S-I and Ge-As-S based multimaterial fibers for the production of IR laser sources between 3 and 5 µm, will be presented. The last chapter will present the project, the methodology and the results obtained to realize multimaterial fibers with ZnS core, using two different technics.

Tong Yu Chung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references. / Abstract --- p.i / Acknowledgments --- p.ii / Table of Contents --- p.iii / Chapter (1) --- Introduction --- p.1 / Chapter 1.1 --- Background --- p.1 / Chapter 1.2 --- Overview of the Thesis --- p.2 / References --- p.4 / Chapter (2) --- Review of Ultrashort Pulse Generation and Pulsewidth Measurement --- p.5 / Chapter 2.1 --- Introduction --- p.5 / Chapter 2.2 --- Q-switching --- p.5 / Chapter 2.3 --- Gain-switching --- p.8 / Chapter 2.4 --- Mode-locking --- p.11 / Chapter 2.4.1 --- Active mode-locking --- p.12 / Chapter 2.4.2 --- Passive mode-locking --- p.13 / Chapter 2.5 --- Optical Pulse Compression --- p.15 / Chapter 2.6 --- Pulsewidth Detection Methods --- p.18 / Chapter 2.6.1 --- Streak camera --- p.18 / Chapter 2.6.2 --- Photodetector and sampling oscilloscope --- p.20 / Chapter 2.6.3 --- Nonlinear autocorrelator --- p.21 / Chapter 2.6.4 --- Other techniques --- p.24 / References --- p.25 / Chapter (3) --- Erbium Doped Fiber Amplifier and Active Mode-locking --- p.28 / Chapter 3.1 --- Introduction --- p.28 / Chapter 3.2 --- Erbium Doped Fiber Amplifier --- p.28 / Chapter 3.2.1 --- Background --- p.28 / Chapter 3.2.2 --- Experiment --- p.31 / Chapter 3.3 --- Additive Pulse Mode-locking --- p.35 / Chapter 3.4 --- Active Mode-locking --- p.37 / Chapter 3.4.1 --- Background --- p.37 / Chapter 3.4.2 --- Experiment and result --- p.38 / Chapter 3.4.3 --- Discussion --- p.43 / Chapter 3.5 --- Chapter Summary --- p.46 / References --- p.46 / Chapter (4) --- Passive Mode-locking of Erbium Doped Fiber Laser --- p.49 / Chapter 4.1 --- Introduction --- p.49 / Chapter 4.2 --- Background --- p.49 / Chapter 4.3 --- Experimental Setup --- p.51 / Chapter 4.4 --- Initialing Mode-locking --- p.54 / Chapter 4.5 --- Experimental Result --- p.55 / Chapter 4.5.1 --- Real time pulse train --- p.55 / Chapter 4.5.2 --- Autocorrelation trace --- p.57 / Chapter 4.5.3 --- RF spectrum --- p.58 / Chapter 4.5.4 --- Optical spectrum --- p.59 / Chapter 4.5.5 --- Time-bandwidth product --- p.60 / Chapter 4.5.6 --- Output power --- p.61 / Chapter 4.6 --- Discussion --- p.63 / Chapter 4.6.1 --- Linear pulse broadening --- p.63 / Chapter 4.6.2 --- Cavity oscillation --- p.65 / Chapter 4.6.3 --- Pump power hysteresis --- p.66 / Chapter 4.6.4 --- Sideband generation --- p.67 / Chapter 4.6.5 --- Spectral distortion --- p.68 / Chapter 4.7 --- Chapter Summary --- p.71 / References --- p.72 / Chapter (5) --- Application of Ultrashort Optical Pulses from Figure Eight Laser --- p.74 / Chapter 5.1 --- Introduction --- p.74 / Chapter 5.2 --- Dispersion Measurement --- p.74 / Chapter 5.2.1 --- Introduction --- p.74 / Chapter 5.2.2 --- Background --- p.75 / Chapter 5.2.3 --- Experiment and result --- p.76 / Chapter 5.2.4 --- Discussion and conclusion --- p.80 / Chapter 5.3 --- Time Domain Spectral Estimation --- p.82 / Chapter 5.3.1 --- Introduction --- p.82 / Chapter 5.3.2 --- Background --- p.82 / Chapter 5.3.3 --- Experiment and result --- p.83 / Chapter 5.3.4 --- Discussion --- p.88 / Chapter 5.4 --- Ultrashort Pulse Amplification --- p.89 / Chapter 5.4.1 --- Introduction --- p.89 / Chapter 5.4.2 --- Background --- p.89 / Chapter 5.4.3 --- Experiment and result --- p.92 / Chapter 5.4.4 --- Discussion and conclusion --- p.95 / References --- p.96 / Chapter (6) --- Picosecond Pulse Generation from Semiconductor Laser Diodes --- p.99 / Chapter 6.1 --- Introduction --- p.99 / Chapter 6.2 --- Gain-switching --- p.99 / Chapter 6.2.1 --- Experiment using commercial laser diodes --- p.99 / Chapter 6.2.2 --- Repetition rate multiplication --- p.102 / Chapter 6.2.3 --- Pulse compression with HDSF --- p.107 / Chapter 6.2.4 --- Fiber loop compressor --- p.110 / Chapter 6.3 --- Active or Hybrid Mode-locking --- p.112 / Chapter 6.3.1 --- Introduction --- p.112 / Chapter 6.3.2 --- Laser structure --- p.113 / Chapter 6.3.3 --- Experiment and result --- p.113 / Chapter 6.3.4 --- Discussion and conclusion --- p.116 / Chapter 6.4 --- Amplifier Modulation --- p.117 / Chapter 6.4.1 --- Introduction --- p.117 / Chapter 6.4.2 --- Experiment and result --- p.118 / Chapter 6.5 --- Wavelength Tuning --- p.120 / Chapter 6.5.1 --- Introduction --- p.120 / Chapter 6.5.2 --- Experiment and result --- p.121 / Chapter 6.5.3 --- Conclusion --- p.123 / Chapter 6.6 --- Chapter Summary --- p.124 / References --- p.124 / Chapter (7) --- Conclusion --- p.126 / Chapter 7.1 --- Summary of the Research --- p.126 / Chapter 7.1.1 --- Fiber lasers --- p.126 / Chapter 7.1.2 --- Diode lasers --- p.128 / Chapter 7.2 --- Further Study --- p.129 / Appendix I Project Instrumentation --- p.A-l / Appendix II Curve Fitting Program for the SHG Autocorrelation Trace --- p.A-8 / Appendix III Experiment Setup of Figure Eight Laser --- p.A-12 / "Appendix IV Curve Fitting Program for Determination of Second Order Dispersion, dD/dλ" --- p.A-14 / Appendix V 1.3 μm two sections DFB/TA Laser Diode Chips --- p.A-17 / Appendix VI Publication List --- p.A-l9

Neste trabalho, apresentamos uma anÃlise numÃrica para a obtenÃÃo de portas lÃgicas totalmente Ãpticas, baseadas em um Acoplador Direcional NÃo-Linear Duplo SimÃtrico (NLDC) em fibras de cristais fotÃnicos (PCF) sem perda, trabalhando com pulsos ultracurtos de 100 fs(femtosegundos), para a obtenÃÃo de portas lÃgicas E/OU, sob ModulaÃÃo por PosiÃÃo de Pulsos (PPM). A investigaÃÃo à realizada atravÃs de simulaÃÃes numÃricas, utilizando-se o mÃtodo de Runge-Kutta de quarta ordem. Considerando a operaÃÃo das portas lÃgicas, foram utilizadas as quatro possÃveis combinaÃÃes para dois pulsos nas entradas das fibras 1 e 2, modulados pela posiÃÃo temporal (PPM) nos nÃveis lÃgicos 0 ou 1. Foram investigados, inicialmente, os efeitos de uma variaÃÃo no parÃmetro de ajuste PMM (ε) no deslocamento do pulso de saÃda em cada uma das fibras; em seguida, foram investigados os efeitos da diferenÃa de fase(ΔФ) entre os pulsos sÃlitons fundamentais de entrada, devidamente modulados, no deslocamento do pulso de saÃda em cada uma das fibras. Nas duas aplicaÃÃes, foram levados em consideraÃÃo a dispersÃo de velocidade anÃmala de grupo (GVD), a dispersÃo de segunda ordem (β2), a dispersÃo de terceira ordem (β3) e os efeitos nÃo-lineares SPM, SS e IRS. Os resultados indicam que à possÃvel a obteÃÃo de portas lÃgicas OU utilizando um controle de fase para um pulso de entrada. / In this work, we present a numerical analysis for obtaining all-optical logic gates based on a Directional Coupler Nonlinear Symmetric Double (NLDC) in photonic crystal fibers (PCF) without loss, working with ultrashort pulses of 100 fs (femtoseconds) , to obtain gates AND / OR under Pulse Position Modulation (PPM). Research is conducted through numerical simulations, using the Runge-Kutta fourth order. Considering the operation of logic gates were used the four possible combinations to the inputs of two pulses fibers 1 and 2, the temporal position modulated (PPM) in the logic levels 0 or 1. Were investigated initially, the effects of a change in tuning parameter PMM (ε) in the displacement of the output pulse in each fiber, then we investigated the effects of the phase difference (ΔФ) between pulses of fundamental solitons input, suitably modulated, at offset output pulse in each fiber. In both applications, were considered anomalous dispersion of group velocity (GVD), second order dispersion (β2), the third-order dispersion (β3) and nonlinear effects SPM, SS and IRS. The results indicate that it is possible to achievement OR logic gate using phase control to an input pulse.

The design, processing, and sequential testing of a novel cylindrical diffusing optical fiber tip for ultraviolet light delivery is described. This device has been shown to uniformly(+/- 15%) illuminate angioplasty balloons, 20 mm in length, that are used in an experimental photochemotherapeutic treatment of swine intimal hyperplasia. Our experiments show that uniform diffusing tips of < 400 micron diameter can be reliably constructed for this and other interstitial applications. Modeling results indicate that this design is scalable to smaller diameters. The diffusing tips are made by stripping the protective buffer and etching away the cladding over a length of 20 mm from the fiber tip and replacing it with a thin layer of optical epoxy mixed with A/203 powder. To improve the uniformity and ease of fabrication, we have evaluated a new device configuration where the tip is etched into a modified conical shape, and the distal end face is polished and then coated with an optically opaque epoxy. This is shown to uniformly scatter - 70% of the light launched into the fiber without forward transmission. To our knowledge, we are the first to use this device configuration, and we have achieved a uniform cylindrical pattern of laser energy with uniformity < ± 15% of the average value. A simple computational model suitable for the interpretation of laser energy irradiance along the bare core surface of multimode optical fiber tips is proposed and experimentally verified. The model used is based on geometrical optics and Gaussian approximation. Good agreement is obtained between the calculation and experiment. We have measured the optical properties of the tips through all the sequences of the fabrication. The performances of the diffusing tips for illuminating angioplasty balloons are then evaluated by Ultraviolet Light at 365 nm. A Ti:Sapphire Ring Laser System with a doubling crystal pumped by an argon ion laser is used to generate the wavelength in this study.

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (p. 140-144).

Conventional step-index silica fibers do not possess a second-order optical nonlinearity due to symmetry concerns. However, through the process of poling, the generation of a frozen-in DC field $E^{DC}$, and in turn, a non-zero second-order nonlinearity $\chi^{(2)} = 3\chi^{(3)}E^{DC}$, can be created in optical fibers. In this thesis, I measure the individual $\chi^{(2)}$ tensor elements of birefringent periodically poled fiber via second-harmonic generation and sum-frequency generation experiments. The symmetry of the $\chi^{(2)}$ tensor is consistent with that of the $\chi^{(3)}$ for isotropic media. This is the first study that characterizes all the $\chi^{(2)}$ tensor elements in birefringent poled fiber. Furthermore, I investigate the intermix of the $\chi^{(2)}$ tensor elements by twisting the fiber, which results in the generation of new second-harmonic signals not observed in untwisted fiber. The conversion efficiencies and spectral positions of these new signals can be varied by twisting the fiber.

Conventional step-index silica fibers do not possess a second-order optical nonlinearity due to symmetry concerns. However, through the process of poling, the generation of a frozen-in DC field $E^{DC}$, and in turn, a non-zero second-order nonlinearity $\chi^{(2)} = 3\chi^{(3)}E^{DC}$, can be created in optical fibers. In this thesis, I measure the individual $\chi^{(2)}$ tensor elements of birefringent periodically poled fiber via second-harmonic generation and sum-frequency generation experiments. The symmetry of the $\chi^{(2)}$ tensor is consistent with that of the $\chi^{(3)}$ for isotropic media. This is the first study that characterizes all the $\chi^{(2)}$ tensor elements in birefringent poled fiber. Furthermore, I investigate the intermix of the $\chi^{(2)}$ tensor elements by twisting the fiber, which results in the generation of new second-harmonic signals not observed in untwisted fiber. The conversion efficiencies and spectral positions of these new signals can be varied by twisting the fiber.

Thesis (M.S. in Computer Science)--Naval Postgraduate School, December 2003. / Thesis advisor(s): Bert Lundy, Wen Su. Includes bibliographical references (p. 101-103). Also available online.